diff --git a/sympy/physics/units/quantities.py b/sympy/physics/units/quantities.py
index 8677f7ce57..9ab351f7b7 100644
--- a/sympy/physics/units/quantities.py
+++ b/sympy/physics/units/quantities.py
@@ -130,21 +130,21 @@ def abbrev(self):
         return self._abbrev
 
     @property
-    def scale_factor(self):
+    def _scale_factor(self):
         """
         Overall magnitude of the quantity as compared to the canonical units.
         """
         return Quantity.SI_quantity_scale_factors.get(self, S.One)
 
     def _eval_is_positive(self):
-        return self.scale_factor.is_positive
+        return self._scale_factor.is_positive
 
     def _eval_is_constant(self):
-        return self.scale_factor.is_constant()
+        return self._scale_factor.is_constant()
 
     def _eval_Abs(self):
-        scale_factor = Abs(self.scale_factor)
-        if scale_factor == self.scale_factor:
+        scale_factor = Abs(self._scale_factor)
+        if scale_factor == self._scale_factor:
             return self
         return None
         q = self.func(self.name, self.abbrev)
@@ -179,7 +179,7 @@ def get_dimensional_expr(expr):
     def _collect_factor_and_dimension(expr):
         """Return tuple with factor expression and dimension expression."""
         if isinstance(expr, Quantity):
-            return expr.scale_factor, expr.dimension
+            return expr._scale_factor, expr.dimension
         elif isinstance(expr, Mul):
             factor = 1
             dimension = Dimension(1)
@@ -246,4 +246,4 @@ def convert_to(self, other):
     @property
     def free_symbols(self):
         """Return free symbols from quantity."""
-        return self.scale_factor.free_symbols
+        return self._scale_factor.free_symbols
diff --git a/sympy/physics/units/util.py b/sympy/physics/units/util.py
index 9175c4158b..4dd0263952 100644
--- a/sympy/physics/units/util.py
+++ b/sympy/physics/units/util.py
@@ -119,7 +119,7 @@ def get_total_scale_factor(expr):
         elif isinstance(expr, Pow):
             return get_total_scale_factor(expr.base) ** expr.exp
         elif isinstance(expr, Quantity):
-            return expr.scale_factor
+            return expr._scale_factor
         return expr
 
     depmat = _get_conversion_matrix_for_expr(expr, target_units)
